Much attention has been focused on 141b in recent years as a replacement for CFC-11 (trichlorofluoromethane) as a foam blowing agent, as a solvent, and so forth. In the manufacture of 141b, however, such as by the reaction of hydrogen fluoride with 1,1,1-trichloroethane or vinylidene chloride ("VDC"), unwanted impurities such as unsaturated carbon compounds (including VDC) have been found to result. Thus, processes have been developed for removing VDC from 141b via photochlorination, such as disclosed in U.S. Pat. No. 4,948,479.
It has now been found, however, that even with such a purification procedure 141b can be unstable in storage, resulting in the formation of such unwanted by-products as phosgene. Thus, the industry is in need of a means for producing storage-stable 141b.
As noted in U.S. Pat. No. 5,135,680, 141b also has stability problems in blowing agent applications. As there stated, "Polyurethane and polyisocyanurate foams are conventionally prepared by reacting an organic polyisocyanate (including diisocyanate) `A-side` component with a `B-side` polyol premix component containing organic polyol, blowing agent, surfactant, catalyst, and possibly other additives such as flame retardants, antioxidants, and U.V. stabilizers. These A-side and B-side components may be purchased by the end-user in separate containers and stored for later use. Since decomposition of the HCFC blowing agents has been observed in the B-side premixes during storage and during the process of making the foam, HCFC compositions inhibited against such decompositions would be highly desirable. For example, the preferred 141b blowing agent has been observed to decompose during the foam-making process to up to about 1%, depending on the formulation and reaction conditions, of various decomposition products of which by far the predominant product is 1-chloro-1-fluoroethylene ("1131a"). Inhibition of such decomposition is desired both because of toxicity concerns and because the decomposition is accompanied by the formation of equivalent amounts of acid which in turn causes catalyst deactivation."